package nio;

import java.io.IOException;
import java.nio.ByteBuffer;
import java.nio.channels.SelectionKey;
import java.nio.channels.Selector;
import java.nio.channels.SocketChannel;
import java.nio.charset.Charset;
import java.util.Iterator;
import java.util.Set;

/**
 * 客户端异步监听服务端响应Runnable类
 */
public class ClientThread implements Runnable{
    private Selector selector;

    public ClientThread(Selector selector) {
        this.selector = selector;
    }

    @Override
    public void run() {
        try {
            while (true) {
                // 获取 channel 数量
                int readChannels = selector.select();
                if (readChannels == 0) continue;

                // 获取可用的channel
                Set<SelectionKey> selectionKeys = selector.selectedKeys();
                // 遍历集合
                Iterator<SelectionKey> iterator = selectionKeys.iterator();
                while (iterator.hasNext()) {
                    SelectionKey selectionKey = iterator.next();
                    // 移除 set 集合当前 selectionKey
                    iterator.remove();
                    // 如果可读状态操作
                    readOperator(selector, selectionKey);
                }
            }
        }catch (Exception e) {
            e.printStackTrace();
        }
    }

    private void readOperator(Selector selector, SelectionKey selectionKey) throws IOException {
        // 1、从 selectionKey 获取到已经就绪的通道
        SocketChannel socketChannel = (SocketChannel)selectionKey.channel();
        // 2、创建buffer
        ByteBuffer byteBuffer = ByteBuffer.allocate(1024);
        // 3、循环读取客户端消息
        int readLength = socketChannel.read(byteBuffer);
        String message = "";
        if (readLength > 0) {
            // 切换读模式
            byteBuffer.flip();
            // 读取内容
            message += Charset.forName("UTF-8").decode(byteBuffer);
        }
        // 4、将channel再次注册到选择器上，监听可读状态
        socketChannel.register(selector, SelectionKey.OP_READ);
        // 5、把客户端发送消息，广播到其他客户端
        if (message.length() > 0) {
            // 广播给其他客户端
            System.out.println(message);
        }
    }
}
